Yahoo is especially bad in that every free utility on the web is trying to install it on my machine.  Usually an opt-out situation where I have to remember to uncheck the magic box.  Adobe Acrobat and Shockwave now try and install it (and others).  MSN Desktop search isn’t much better in that is forces you to use the MSN toolbar (and I cannot even disable or hide it).  I just want my google toolbar, none of the others.  Arg!